Tuesday, November 26, 2013

A complete example of drawing text using DirectWrite APIs

a complete example of using DirectWrite to draw text. the procedure is to create a customized brush, set text format, and then call the DrawTextLayout()


CComPtr<ID2D1SolidColorBrush>  m_pSolidColorBrush;
CComPtr<IDWriteTextLayout> m_pTextLayout_;
CComPtr<IDWriteFactory> m_pDWriteFactory_;
CComPtr<IDWriteTextFormat> m_pTextFormat_;
const wchar_t* m_wszText_;
UINT32 m_cTextLength_;
D2D1_POINT_2F m_origin;



// the following init are used for text drawing -

       // create a customized brush
       m_hWndTarget->CreateSolidColorBrush(
              D2D1::ColorF(D2D1::ColorF::Purple, 1.0f),
              &m_pSolidColorBrush
              );

       D2D1_SIZE_F rtSize = m_hWndTarget->GetSize();
       int width = static_cast<int>(rtSize.width);
       int height = static_cast<int>(rtSize.height);         
       // draw text now
       m_origin = D2D1::Point2F(
              static_cast<FLOAT>(rect.left / 4),
              static_cast<FLOAT>(rect.top / 4)
              );
                    
       m_wszText_ = L"Hello World using  DirectWrite!";
       m_cTextLength_ = (UINT32)wcslen(m_wszText_);

       DWriteCreateFactory(
              DWRITE_FACTORY_TYPE_SHARED,
              __uuidof(IDWriteFactory),
              reinterpret_cast<IUnknown**>(&m_pDWriteFactory_)
              );

       //create a customized text format
       m_pDWriteFactory_->CreateTextFormat(
              L"Gabriola",                // Font family name.
              NULL,                       // Font collection (NULL sets it to use the system font collection).
              DWRITE_FONT_WEIGHT_REGULAR,
              DWRITE_FONT_STYLE_NORMAL,
              DWRITE_FONT_STRETCH_NORMAL,
              32.0f, //72.0f,  // font size
              L"en-us",
              &m_pTextFormat_
              );

       //create text layout
       m_pDWriteFactory_->CreateTextLayout(
              m_wszText_,      // The string to be laid out and formatted.
              m_cTextLength_,  // The length of the string.
              m_pTextFormat_,  // The text format to apply to the string (contains font information, etc).
              width,         // The width of the layout box.
              height,        // The height of the layout box.
              &m_pTextLayout_  // The IDWriteTextLayout interface pointer.
              );

//jamesz: actual text drawing function here, can call this once per frames
              if (1)
              {
                     m_hWndTarget->DrawTextLayout(
                           m_origin,
                           m_pTextLayout_,
                           m_pSolidColorBrush
                           );                  

              }

posted by jameszhou2000 @ 5:49 PM

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